Blood, Breath and Urine Testing

Iowa Datamaster Breath Test Device

Far and away, the most popular evidentiary test given to motorists to determine their alcohol concentration in the State of Iowa is breath.  The initial decision on what type of bodily fluid to request for purposes of chemical testing is the arresting officer's.  The officer may request, breath, blood or urine.  Under most circumstances this request is being made at the police station after the person has been arrested.  In these circumstances, breath is what is ordinarily requested because the breath test machine is installed and presumably functioning there at the police station.  These tests are inexpensive to administer and take approximately 3-5 minutes.     

Iowa DataMaster DMT

Iowa now uses the DataMaster DMT breath testing device, initially produced by National Patent Analytical Systems, Inc., based out of Mansfield, Ohio. ( 

The DataMaster DMT uses infrared absorption spectrometry technology to measure the concentration of alcohol molecules in the breath sample submitted into the machine.  This machine measures both the alcohol concentration in the individual’s breath sample but also the volume of breath submitted as well.  

Iowa DataMaster Graph

In Iowa, the machine is programmed to print out a graph that shows both the alcohol concentration curve as well as the breath volume curve.

The purpose of the breath volume curve is to provide a visual display of the “quantity” of breath sample being provided into the machine for the test.

This graph display theoretically will limit arguments from either side that the individual submitting to the test either did or did not provide an adequate sample of their breath for the test. 

Final Breath Test Results

To prevent officer and test subject “manipulation,” the machine does NOT display a numeric test result until the end of the test, when the sample is accepted and the test is complete. 

The final results are printed off to the left of the graft and may look like the above image.

The “subject sample” is the numeric test result that is reported.  The same breath sample is tested twice by the machine.

Iowa State Requirements to Use Breath Test Results as Evidence

There are a number of requirements that must be followed before an evidential breath test result may be admitted against an individual in an operating while intoxicated case.

  1. The implied consent procedures must have been properly followed.
  2. The officer must be certified to operate the breath test device. 
  3. A certified breath test machine must be used.
  4. The officer must follow the proper procedures set forth by the Iowa Department of Criminal Investigation. These procedures include a 15 minute deprivation period that absolutely must be followed in every case.

If the basic evidential foundational requirements are met, the test result can be presented to the jury and the question becomes whether or not the breath test accurately represents the subjects true alcohol concentration at the time they were operating the vehicle.  This is where defenses such as rising alcohol, mouth alcohol, interfering medical conditions such as Acid Reflux or GERD, partition ration, margin of error, statistical uncertainty, electronic interference, and others, may come into play.

Urine Testing

Urine testing in drunk driving investigations is the least reliable of the least desirable form of chemical testing, especially for alcohol.  The most significant problem with urine testing is that it simply reveals what was in the person’s bloodstream at a prior time, NOT at the time they are being tested.  It is also the most volatile easily contaminated bodily substance that can be tested in DUI investigations.

In alcohol cases, the urinalysis only tells law enforcement the average alcohol concentration that has been through the persons system since the last time their bladder had been emptied.  This is because alcohol molecules detected in urine are simply the waste product of what has already been processed through the blood stream, secreted by the kidneys.  Once processed through the body, the alcohol molecules then sit in the bladder as more urine is produced which will either have a greater or less concentration than what was previously produced.  The result is something commonly referred to as the “pooling effect.”  This results in merely averaging of the concentration of alcohol molecules that have been in the person’s blood stream since the last time the bladder was emptied.

While Iowa, like many States, does not require a correlation of alcohol in the urine to a particular blood concentration at the time of driving for ordinary operating while intoxicated prosecutions, the deficiencies in urine testings’ ability to be correlated to a blood alcohol concentration is of significant importance in Vehicular Homicide and Serious Injury by Vehicle cases.  In those cases, the State is required to prove that the individual’s intoxication was the cause in fact of the accident.  It is not enough to prove that the person simply had a particular level of alcohol or drug in their system and that an accident happened.  Rather, the State is required to prove that the person was impaired by the substance and that such impairment was a cause of the collision.  In these cases the deficiencies in urine testings’ ability to correlate to a specific blood concentration and corresponding level of impairment, becomes paramount to an effective defense.

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